Facet- and defect-dependent activity of perovskites in catalytic evolution of sulfate radicals

The soaring pressure on clean environment urges for high-performance and robust catalysts in water treatment to secure the sustainability of water resources. In this work, shape-controlled perovskites La0.5Ba0.5CoxMn1-xO3-δ (LBCxM1-x) were applied as peroxymonosulfate (PMS) activators to generate reactive oxygen species (ROS) for water purification. Owing to the presence of abundant oxygen vacancies and low-valence Co2+ cations, cubic-shaped LBC0.8M0.2 exhibited a much higher catalytic activity than octahedral LBC0.2M0.8 with a better structural stability and controlled metal leaching. Iodometric titration and solid electron paramagnetic resonance (EPR) validated that an increase of Co/Mn ratios would produce abundant oxygen vacancies as active sites to bond with and activate PMS molecules, facilitated by the redox couples of Co2+/Co3+ and Mn3+/Mn4+. Competitive radical tests and in-situ EPR spectra suggested that SO4•− was the dominant ROS. This study provides new insights into the structure-performance relationship of shape- and defect-dependent perovskites in environmental catalysis.